# A Core Effector MoPce1 Is Required for the Pathogenicity of Magnaporthe oryzae by Modulating Catalase‐Mediated H2O2 Homeostasis in Rice

## TL;DR

A key protein from a rice fungus helps it infect plants by disrupting the plant's oxygen balance, making the plant more vulnerable.

## Contribution

MoPce1 is identified as a novel core effector that modulates catalase-mediated ROS homeostasis to promote pathogenicity.

## Key findings

- MoPce1 is essential for pathogenicity but not for asexual development in Magnaporthe oryzae.
- MoPce1 interacts with rice catalase OsCATC to suppress reactive oxygen species (ROS) burst in rice.
- Disruption of OsCATC enhances rice blast resistance and increases ROS production.

## Abstract

Plant pathogens employ a diverse array of effectors to facilitate host colonisation, including evolutionarily conserved core effectors. In this study, we identified MoPce1, a CAP/PR‐1 domain‐containing protein widely distributed among fungal species, as a key virulence factor in Magnaporthe oryzae. Among 72 putative core effectors (PCEs), MoPce1 was found to be essential for pathogenicity but dispensable for asexual development. It localises to biotrophic interfacial complex (BIC) in invasive hyphae (IHs) and to the cytoplasm in Nicotiana
benthamiana leaves and rice protoplasts. Ectopic expression of a signal peptide‐deleted variant of MoPCE1 (MoPCE1

Δsp
) in rice compromised blast resistance and suppressed the reactive oxygen species (ROS) burst. Notably, MoPce1 lacks the conserved cysteine residues essential for sterol‐binding in the CAP domain, suggesting its potential association with a novel ligand. Further investigation revealed that MoPce1 interacts with rice catalase OsCATC, specifically via the C1 fragment (231–360 aa). Disruption of OsCATC (oscatc) enhanced rice blast resistance and triggered a stronger ROS burst. Collectively, our results indicate that MoPce1 targets OsCATC to disrupt ROS homeostasis and suppress host immunity, thereby facilitating infection.

MoPce1, an atypical CAP/PR‐1 family effector, is essential for Magnaporthe oryzae virulence. MoPce1 functions by interacting with the rice catalase OsCATC to disrupt ROS homeostasis, thereby promoting host susceptibility.